Josef haslauer



J. HASLAUER Sept. 21 1926. 1,600,233H

voLTMETER Filed Oct., 10. 1925 i lvenJfof Josef' Haflaue'r 1is /lHox-neg Patented Sept. 21, 1926.

JOSEF 'HASLAUEIM OF MUNICH, GERMANY.

VOLTMETER.

Application led October l0, 1925, Serial No.- 61,803, and in Germany August 19, 1924.

The invention relates to voltmeters, more particularly pocket roltmeters, for direct and alternating currents. Its object 1s to provide a simple instrument, which can be cheaply made and is su'licicntly accurate t0 indicate, with good or fair approximation, the voltage ot the current in a circuit 1n caacs where it is desired to ascertain to What order ot 'values the vvoltage belongs, rather than to measure with precision.

According to the invention a hollow cylinder oi magnetiic material is so disposed around the armature and in relation to the oil producing the magnetic flux, that nearly the whole ot the linx passes through this c vlinder, but the latter is provided with a siot or gap in which there is a field whose strength varies, from one part to another, and the armature, which is biased in the usual way, tends to move into the strongest part of this field.

The invention is illustrated in the vaccompanying drawing, which shows an embodiment thereof,

Figure l being a'section perpendicular to the axis ot the instrument, and

Fig. .2 a section on the line A-B of Fig. l;

Fig. S'shows, developed in a plane, the cylindriral casing already referred to;

4 shows another modification of the armature Fig. 5 4is a t'ront elevation of the instruf ment;

Figure 6 is a view corresponding'to Figure 3 except that the opening 0 is shown as` having curved sides.

4'Yi/lithin the outer casing 7; of insulating material, which has a glass face Z, there is an annular iron box a, the inner circumferential wall ot which is an iron cylinder b having a slot c. The width of the latter' decreases from one end to the other, but instead ot' being tapered with straight lateral edges, as shown in solid lines in Fig. 3, the edges may be curved, as shown in broken lines. Within the box, and seated upon the cylinder l), there is a coil holder cl, with a coil of resistance wire wound thereon, the ends of the coil beingr connected to posts e. IVithin the cylinder b is mounted the armature f, which may be a segment of a cylinder, as shown in F ig. l, or a complete cylinder. as shown in Fig. 4. To the armature spindle are attached a pointer hand one end of a non-magnetic spiral spring Vg. The

specification.

armature'spindle is slightly eccentric in re I lation to the cylinder b. The scale z' is' marked on the box a.

When the terminals of tl e coil are connected to a live circuit, the t magnetic tlux which is almost wholly confined to the iron box a and cylinder b, but there is in the slot c a stray field, Whose strength varies from one end to the other. The armature f, which by virtue of its eccentric mounting can swing into the slot, tends ot' course to occupy the strongest part ot' the tield.

The instrument shown can be used for direct and alternating currents, but different scales are required for these two kinds oit current.

What I claim as my invention and desire" to secure by Letters Patent of the United States is l. In a voltmeter, the combination with an outer 'asiug ot insulating material, of a tiel'd magnet coil in said casing, an annular box of magnetic material .within said casing and completely enclosing said coil, the inner wall of said box being acylinder having a slot varying .in width from one end Ato the other', and an eccentrically mounted armature movable interiorly of said cylinder.

2. In a voltmeter, the combination ot' an outer casing of insulating material having a transpanentvglass face therefor, an annular ironliollow member arranged concentrically within said casing, the inner wall thereof being substantially thicker than the side and outside Walls and provided with a slot disposed circumterentially of the inner wall and having its longitudinal side walls tapered towards each other, a coil holder arranged about the inside of the inner Wall of the member and having a coil of resistance wire Wound thereon, posts carried by the casing and Areceiving the ends of said resisance wire, an armature operating Within said inne'r wall, a spindle for said armature disposed eccentrically of the axis of said inner wall, a pointer for the spindle and operating to indicate over a'scale below the glass face, and a. balance spring disposed about the spindle and operating to yieldably hold the armature' in a predetermined position and the pointer at zero on the scale.

In Witness whereof I have signed this JOSEF HASLAUER.

oil generates a l 

